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-   -   Reasons why kmem slab cache mapping does not work on SLES 9 and lkcd dump (http://www.linux-archive.org/crash-utility/323478-reasons-why-kmem-slab-cache-mapping-does-not-work-sles-9-lkcd-dump.html)

"Laurence A. Oberman" 02-09-2010 10:29 PM

Reasons why kmem slab cache mapping does not work on SLES 9 and lkcd dump
 
Hi Dave,

Thanks, yes it is a 32GB configuration.

Based on my dump here, (which was a kernel pages only dump),it is indeed missing that memory address at the end of the list. The last address is 82fffe000.

I forced the dump for DLM lock problem which I understand and was able to research, but the SLAB stuff has never worked for me on SLES 9.

This may just be a bug with lkcd. I never have these problems on Redhat with kdump.

I will test it on a SLES 11 running kdump and see what happens


crash> kmem -p | tail
1001da7fd98 82fff5000 0 0 0 1000080
1001da7fdd0 82fff6000 0 0 0 1000080
1001da7fe08 82fff7000 0 0 0 1000080
1001da7fe40 82fff8000 0 0 0 1000080
1001da7fe78 82fff9000 0 0 0 1000080
1001da7feb0 82fffa000 0 0 0 1000080
1001da7fee8 82fffb000 0 0 0 1000080
1001da7ff20 82fffc000 0 0 0 1000080
1001da7ff58 82fffd000 0 0 0 1000080
1001da7ff90 82fffe000 0 0 0 1000080

crash> sys
SYSTEM MAP: map.0
DEBUG KERNEL: vmlinux (2.6.5-7.244-smp)
DUMPFILE: dump.0
CPUS: 4
DATE: Sat Feb 6 12:43:37 2010
UPTIME: 213503982289 days, 20:38:24
LOAD AVERAGE: 260.75, 259.77, 258.95
TASKS: 1167
NODENAME: linuscs73
RELEASE: 2.6.5-7.252-smp
VERSION: #2 SMP Mon Jun 22 13:11:57 PDT 2009
MACHINE: x86_64 (2666 Mhz)
MEMORY: 32.7 GB
PANIC: "manual"
crash>

The "seek error" indicates that the kmem slab page associated with
virtual address 1082fffea00, which is unity-mapped to physical
address 82fffea00, could not be found in the dump.0 file.

If we presume that it is a "correct" address, physical address
82fffea00 is *very* close to the end of physical memory on that
system, which shows "32.7 GB". If you enter:

crash> kmem -p | tail

and wait a while because of the size of the dump, it will eventually
dump the end of the system's mem_map array of physical pages, where
the second column in the list contains the physical address.

I only have one SLES9 (2.6.5-7.315-smp) dumpfile example, which is
a 16GB dumpfile, and the output looks like this:

crash> kmem -p | tail
10407efdd98 407ff5000 0 0 0 d000080
10407efddd0 407ff6000 0 0 0 d000080
10407efde08 407ff7000 0 0 0 d000080
10407efde40 407ff8000 0 0 0 d000080
10407efde78 407ff9000 0 0 0 d000080
10407efdeb0 407ffa000 0 0 0 d000080
10407efdee8 407ffb000 0 0 0 d000080
10407efdf20 407ffc000 0 0 0 d000080
10407efdf58 407ffd000 0 0 0 d000080
10407efdf90 407ffe000 0 0 0 d000080
crash>

where 407ffe000 is the last page of physical memory on the system.

If you do the same thing, how does the last physical page compare
to 82fffea00?

Dave



output looks like this




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